1. Field of the Invention
The invention relates to a process for the preparation of a sulfided catalyst and the use of the thus prepared catalyst in the hydrotreatment of hydrocarbon feeds.
2. Prior Art
In the oil industry many processes are known in which hydrocarbon-containing feeds are catalytically treated with hydrogen, such as hydrodesulfurizing, hydrodenitrogenizing, and hydrocracking. In such processes use is made of catalysts built up from a carrier material such as alumina, on which there are deposited one or more catalytically active metals or compounds thereof; examples of such metals include molybdenum, nickel, cobalt, and tungsten. It is common knowledge that optimum results are obtained in using such catalysts when the catalytically active metals are in their sulfided form.
In actual practice sulfiding is generally carried out in situ, i.e. in the reactor in which the final hydrotreatment of the hydrocarbon-containing feed is carried out. Having been introduced into the reactor, the fresh or regenerated catalyst during the start-up procedure is contacted at elevated temperature with a hydrogen gas stream mixed with a sulfiding agent or a hydrogen gas stream combined with a hydrocarbon-containing feed containing an added sulfiding agent (a so-called spiked feed), said sulfiding agent being either hydrogen sulfide or a compound that under the prevailing conditions is decomposable into hydrogen sulfide. In this connection see, a.o., H. Hallie's article in Oil & Gas Journal, Dec. 20, 1982, Technology, pp. 69-74.
A recent development in this field is so-called ex situ presulfiding. In this process the fresh or regenerated catalyst in a first step is treated (impregnated) with a sulfur compound, e.g. a polysulfide, outside the reactor in which the final hydrotreatment of hydrocarbon-containing feed is carried out, and then, if necessary, dried. Next, in a second step, the material is treated with hydrogen gas in the presence or not of a feed in the reactor (in situ) at elevated temperature to activate the catalyst, i.e. bring it into the sulfided state. In this connection see European Patent Applications 0,153,233 and 0,352,851 and U.S. Patent No. 4,530,917 an equivalent of European patent application 0,130,850 and French patent application 83 11048.
Although sulfided catalysts of acceptable activity are produced by either in situ or ex situ presulfiding, it has surprisingly been found that sulfided catalysts of even greater activity can be obtained by a preparative process that combines both methods.